Get counter documents from couchbase view

Question

We using Couchbase's increment function to store some counters on variable keys with constant prefix SomePrefix_. We define view that get all documents which keys start with SomePrefix_:

function (doc, meta) {
  if (meta.id.indexOf("SomePrefix_") === 0) {
    emit(meta.id, doc);
  }
}

When we query the view we get values like "Mg==", "MQ==" etc. .NET SDK fails to load view results and map it to integers.

Any workarounds?

It looks like the view-engine is treating the counter as binary and has converted it to base64. — Paddy, May 22 '15 at 12:08
Yep. They are base64 endoded. .NET SDK 2.0 (NuGet package version 2.0.2) — ilyabreev, May 22 '15 at 16:08

score 2 · Accepted Answer · answered May 25 '15 at 16:16

First of all a view might not be the best approach here depending on what the objective is. If all the keys are known then it will be quicker to use a CRUD operation and not a view. If the requirements are to use a reduce to find the average or max of all the keys, or the keys are simple not known then a view is the correct way to go about it.

Internal to Couchbase Server counters are store as binary and not JSON. As a result the view engine converts binary into base64. When the doc is decode (decodeBase64(doc)) it will be to a ASCII code. Which needs to be then convert to a string using String.fromCharCode(decode[i]) This needs to be done for each digit in turn.

For example if the counter doc is Mg==, when it is decoded it will have the ASCII code 50 which is the decimal string 2.

This view should do the trick.

function (doc, meta) {
  if (meta.id.indexOf("counter_") === 0) {
    var decode = decodeBase64(doc);
    var value = null;
    for (i = 0; i < decode.length; ++i) {
      if (value == null) {
        value = String.fromCharCode(decode[i]);
      } else {
        value += String.fromCharCode(decode[i]);
      }
    }
    emit(meta.id, parseInt(value));
  }
}

I created a improvement [defect](https://issues.couchbase.com/browse/MB-15129) for this in Couchbase Server. — Paddy, May 25 '15 at 17:45
In my case, the keys are simple not known. That's why a view is the only solution. Thank you for detailed explanation of the problem. And for ticket you opened in Couchbase Server :-) — ilyabreev, May 26 '15 at 07:21

Get counter documents from couchbase view

1 Answers1